1. Field of the Invention
The invention relates to a mobile terminal, communication system using the mobile terminal, and a method of re-connecting a line of the mobile terminal in the communication system, and more particularly to such a mobile terminal, communication system, and a method all of which are capable of accomplishing various functions by sharing data stored by terminals with one another through radio signals.
2. Description of the Related Art
In communication system for mobile terminals which system shares data stored in mobile terminals through radio signals to thereby accomplish various functions, such as simplified portable radio telephone system, since state of radio signals through which a mobile terminal makes communication with a radio base station always varies, it is physically impossible to ensure stable communication, and communication may be interrupted at worst. Hence, the above-mentioned conventional communication system attempts to reduce an area which radio signals can scarcely reach, by increasing the number of radio base stations.
In addition, temporary disconnection between a mobile terminal and a radio base station occurs when a mobile terminal passes through an area in which an electric field is locally weak even in a service area, such as intermediate area between buildings and a tunnel in a high-way in an urban area. When a mobile terminal is re-connected after such disconnection has occurred, there is caused a problem that it is not always clear as to which of a mobile terminal and a radio base station should give a call to an opponent, and if both simultaneously attempts to re-connect a line to each other, both cannot be connected to each other.
In order to solve such a problem, Japanese Unexamined Patent Publication No. 5-284091 has suggested communication system in which a mobile terminal is designed to transmit information indicating that the mobile terminal would give a call again immediately after the mobile terminal has passed over an area where an electric field is weakened.
Japanese Unexamined Patent Publication No. 6-315006 has suggested another communication system for mobile terminals. In the suggested communication system, when interruption occurs in radio signals between a mobile terminal and a radio base station, such interruption is informed of an interchange station in mobile network. While the mobile network reserves a call, a mobile terminal or a base station keeps transmitting specific message. When the base station or the mobile terminal receives such specific message, the interchange station in mobile network is informed of such receipt from the base station or the mobile terminal, and then, re-connects a line for the reserved call. Thus, re-connection in a line is carried out immediately after a mobile terminal has passed a blind zone.
However, the above-mentioned conventional communication system which attempts to reduce a blind zone by increasing the number of radio base stations is accompanied with problems that an operator who builds radio base stations has to receive too heavy economic burden, and that stable communication in radio signals cannot always be ensured even if the number of radio base stations is increased, since radio signal condition is varied due to various external factors.
In addition, if abrupt interruption in radio signals occurs, a mobile terminal user usually cannot make further communication after such interruption.
Though the communication system suggested in Japanese Unexamined Patent Publication No. 5-284091 carries out the step of transmitting information indicating that the mobile terminal would give a call again immediately after the mobile terminal has passed over an area where an electric field is weakened, when the mobile terminal dials to an opponent terminal, it is impossible for the mobile terminal to make communication with the opponent terminal unless the mobile terminal passes over the blind zone.
It is also impossible for the communication system suggested in Japanese Unexamined Patent Publication No. 6-315006 to make communication, unless a radio base station or a mobile terminal detects the specific message.
In addition, it is impossible for the communication systems suggested in the above-mentioned Publications to make communication, unless a line in radio signals between a radio base station and a mobile terminal returns into normal condition.
Japanese Unexamined Patent Publication No. 6-78075 has suggested communication system to be mounted in an automobile. In the suggested communication system, if a key-lock signal is transmitted while an operation section is being handled, a control section transmits a reservation requesting signal to a data center, and interrupts telephone lines. State just before interruption of the telephone lines is stored in both a storage section of the system and a storage section in the data center. The control section transmits a reservation releasing signal to the data center for re-connection of the telephone lines after transmission of the key-lock signal has been stopped. Then, a menu screen of the state detected just before interruption of the telephone lines is displayed, based on data stored in the storage sections. The data center is transferred into a state detected just before interruption of the telephone lines. In accordance with the communication system, it is no longer necessary to re-start the operation for selection.
Japanese Unexamined Patent Publication No. 8-307949 has suggested communication system for re-connecting mobile terminals. When a user of a calling terminal or a called terminal interrupts connection in a line, communication is ceased. If communication is ceased without interruption being made by a user, the calling terminal gives a call again to the called terminal without a ringer of the called terminal being rung. The called terminal automatically responds to the calling terminal, even if a user of the called terminal carries out a step necessary for responding to a call, thereby a line between the terminals is connected again.
Japanese Unexamined Patent Publication No. 9-261154 has suggested radio signal communication system. In the suggested communication system, a mobile terminal can make communication with a first base station in a first radio signal zone through a first line having a narrow band, and further can make communication with second and third base stations in second and third radio signal zones through a second line having a wide band. Audio data is transmitted through the first line, and graphic data is transmitted through the second line. Both the audio and graphic data is provided with time stamp for establishing synchronization between audio and graphic data. When the second line is interrupted, the graphic data is ceased to transmit. When the second line is recovered, a location at which the graphic data starts to be transmitted is determined by virtue of the time stamp of the audio data having been received in the first line at the time of recovery of the second line. Thereafter, the graphic data is transmitted through the second line.
The above-mentioned problems remain unsolved even in the communication systems suggested in the above-mentioned Publications
In view of the above-mentioned problems, it is an object of the present invention to provide a mobile terminal, communication system using the same, and a method of re-connecting the mobile terminal, all of which are capable of ensuring communication for a user of a mobile terminal even when a line between a mobile terminal and a radio base station is abruptly interrupted and the line does not return to normal state.
In one aspect of the present invention, there is provided a communication system for mobile terminals, including (a) a first mobile terminal, (b) a first radio base station to which the first mobile terminal is connected through radio signals, (c) a second terminal, and (d) a control station through which the first radio base station is connected to the second terminal, the first mobile terminal including an informer which informs the first radio base station of a first telephone number when the first mobile terminal makes communication with the first radio base station, the first telephone number being determined by a user at his/her discretion and being defined as a telephone number to which the second terminal is re-connected when it becomes impossible for the second terminal to make communication with the first mobile terminal, the control station including a memory in which the first telephone number having been notified from the first radio base station is to be stored, the first radio base station including a first informer which informs the control station of disconnection between the first mobile terminal and the first radio base station when connection between the first mobile terminal and the first radio base station is interrupted while the first mobile terminal is in communication with the second terminal, the second terminal including a first annunciator which is controlled by the control station having been informed of the disconnection and annunciates a user of the second terminal to thereby urge a user of the second terminal to dial the first telephone number, the second terminal further including means for giving a call to the first telephone number when a user of the second terminal dials the first telephone number.
In accordance with the above-mentioned communication system, the first annunciator annunciates a user of the second terminal to thereby urge a user of the second terminal to dial the first telephone number, when disconnection between the first mobile terminal and the first radio base station is detected while the first mobile terminal is in communication with the second terminal. Hence, when the first mobile terminal cannot make communication with the second terminal, it is possible to connect a line between the second terminal and a terminal having the first telephone number, if the second terminal dials the first telephone number.
It is preferable that the second terminal is selected as a mobile terminal in mobile network or a fixed terminal in public network.
It is preferable that the communication system for mobile terminals further includes a second radio base station connected to the control station, and wherein the second terminal is a second mobile terminal connected to the second radio base station through radio signals, the second mobile terminal including an informer which informs the second radio base station of a second telephone number when the second mobile terminal makes communication with the second radio base station, the second telephone number being determined by a user at his/her discretion and being defined as a telephone number to which the first mobile terminal is re-connected when it becomes impossible for the first mobile terminal to make communication with the second terminal, the second radio base station including a second informer which informs the control station of disconnection between the second mobile terminal and the second radio base station when connection between the second mobile terminal and the second radio base station is interrupted while the second terminal is in communication with the first mobile terminal, the first mobile terminal including a second annunciator which is controlled by the control station having been informed of the disconnection and annunciates a user of the first mobile terminal to thereby urge a user of the first mobile terminal to dial the second telephone number, the first mobile terminal further including means for giving a call to the second telephone number when a user of the first mobile terminal dials the second telephone number, the memory of the control station storing the second telephone number having been informed of from the second radio base station, the first and second mobile terminals each including a memory for storing the first and second telephone numbers of the first and second mobile terminals.
In accordance with the above-mentioned communication system, the second annunciator annunciates a user of the first mobile terminal to thereby urge a user of the first mobile terminal to dial the second telephone number, when disconnection between the second terminal and the second radio base station is detected. Hence, when the second terminal cannot make communication with the first mobile terminal, it is possible to connect a line between the first mobile terminal and a terminal having the second telephone number, if the first mobile terminal dials the second telephone number.
It is preferable that the first telephone number is a telephone number of a fixed terminal which is other than the first mobile terminal and the second terminal.
It is preferable that a terminal having the first telephone number has a function of recording therein messages transmitted from the second terminal.
It is preferable that the first mobile terminal has a function of recording therein messages transmitted from the second terminal, the first mobile terminal has the first telephone number, the means for dialing to the first telephone number connects a line to a message recording center to thereby record messages transmitted from the second terminal.
It is preferable that the first mobile terminal dials to the first telephone number without being handled to do so, when a predetermined period of time has passed after detection of disconnection between the first mobile terminal and the first radio base station.
In another aspect of the present invention, there is provided a mobile terminal which makes radio communication with a radio base station and also makes radio communication with an opponent terminal in mobile network or in public network through a control station to which the radio base station is connected, including (a) a memory including a first area in which a first telephone number is to be stored and a second area in which a second telephone number is to be stored, the first telephone number being determined by a user of the mobile terminal at his/her discretion and being defined as a telephone number to which the opponent terminal is re-connected when it becomes impossible for the opponent terminal to make communication with the mobile terminal, the second telephone number being determined by a user of the opponent terminal at his/her discretion and being defined as a telephone number to which the mobile terminal is re-connected when it becomes impossible for the mobile terminal to make communication with the opponent terminal, (b) a controller which (b1) transmits the first telephone number to the radio base station when the mobile terminal makes communication with the radio base station, (b2) stores the second telephone number in the second area which number has been transmitted from the opponent terminal after the mobile terminal has been connected to the opponent terminal, (b3) controls the mobile terminal to start communication with the opponent terminal after the second telephone number has been stored in the second area, and (b4) temporarily stops transmitting radio signals to the radio base station when slot error has continued for a predetermined period of time in signals received from the radio base station, and (c) an annunciator which annunciates information to a user of the mobile terminal to thereby urge a user of the mobile terminal to dial the second telephone number, when informed from the radio base station that disconnection between the mobile terminal and the opponent terminal is other than normal disconnection.
It is preferable that the controller controls the mobile terminal to dial the second telephone number without being handled to do so, when a predetermined period of time has passed after the information has been annunciated.
It is preferable that the controller inserts the first telephone number into sub-address data included in a signal for giving a call, transmits a user-inherent sub-address indicated by a sub-address identifying bit for informing that the sub-address data is used as an area for indicating the first telephone number, and extracts the second telephone number out of received data bit of a control channel to thereby store the thus extracted second telephone number in the second area.
In still another aspect of the present invention, there is provided a method of re-connecting a mobile terminal to an opponent terminal through a radio base station which is connected to a control station, including the steps of (a) informing the radio base station of a first telephone number when the mobile terminal makes communication with the radio base station, the first telephone number being determined by a user of the mobile terminal at his/her discretion, (b) informing the opponent terminal of the first telephone number through the radio base station and the control station when the opponent terminal is called, (c) storing a second telephone number transmitted from the opponent terminal, after connection between the mobile terminal and the opponent terminal has been established, the second telephone number being determined by a user of the opponent terminal at his/her discretion, (d) starting communication between the mobile terminal and the opponent terminal, (e) sending messages to the opponent terminal for urging dialing the first telephone number after disconnection sequence has been carried out in the opponent terminal, when disconnection between the mobile terminal and the radio base station has been detected while communication is being made therebetween, and (f) connecting the opponent terminal to the first telephone number when the first telephone number is dialed in the opponent terminal.
In the above-mentioned method, the first and second telephone numbers having been interchanged in the above-mentioned communication system are stored in the first and second mobile terminals. Hence, when abrupt interruption in a telephone line has occurred, a user can dial the first or second telephone number, which ensures a user to make systematic use of the communication system.
There is further provided a method of re-connecting a mobile terminal to an opponent terminal, including the step of connecting the mobile terminal to a first telephone number having been determined in advance by the opponent terminal when disconnection other than normal disconnection occurs between the mobile terminal and the opponent terminal.
It is preferable that the above-mentioned method further includes the step of connecting the opponent terminal to a second telephone number having been determined in advance by the mobile terminal when disconnection other than normal disconnection occurs between the mobile terminal and the opponent terminal.
The advantages obtained by the aforementioned present invention will be described hereinbelow.
In accordance with the present invention, message is annunciated to a user to thereby urge the user to dial the first or second telephone number, when disconnection between the first mobile terminal and the first radio base station or between the second terminal and the second radio base station is detected while the first mobile terminal is in communication with the second terminal. Hence, when the first and second mobile terminal cannot make communication with each other, it is possible to connect a line between the second terminal and a terminal having the first telephone number or between the first mobile terminal and a terminal having the second telephone number, if the second terminal dials the first telephone number or the first mobile terminal dials the second telephone number. As a result, even if a line between the first mobile terminal and the second terminal is not recovered, it is possible for the first mobile terminal or the second terminal to receive message transmitted from the opponent, through a terminal having the first or second telephone number. That is, a terminal which is in a condition for making communication is able to smoothly dial a telephone number having been informed of in advance for re-connection, without any difficulty in a user.
In accordance with the present invention, it is possible to ensure stable communication between terminal users in radio signal communication system without increasing the number of radio base stations and without economic burden on a system operator.
The above and other objects and advantageous features of the present invention will be made apparent from the following description made with reference to the accompanying drawings, in which like reference characters designate the same or similar parts throughout the drawings.